<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<title></title>
	</head>
	<script>
		var a = 10;
		var b = 10;
		
		function f1()
		{
			var a = 20;
			b = 20;
			return "a="+b+"，b="+b;
		}
		alert(f1());
		alert("a="+a+",b="+b);
	</script>
	<body>
	</body>
</html>
